This invention relates to electric power distribution systems in general and to load centers for such systems and more particularly to the busbars and the contact stabs on the busbars used in such systems.
The present invention is particularly adapted for use in a load center of the type shown in U.S. Pat. No. 3,349,292 issued Oct. 24, 1967 to James F. Meacham, and this patent is incorporated herein by reference, particularly with respect to its showing of an environment in which the present invention might be used and its description of an arrangement of busbars in single phase and three phase installations. See also U.S. Pat. Nos. 3,402,328 and 3,767,977.
A busbar of the type adapted for the present invention comprises an elongated strip or ribbon of conductive material. Projecting above one surface of the strip at spaced intervals along its length are a plurality of stab connections to be plugged into stab receiving cooperating contacts at the line side of a circuit breaker, or the like equipment. Hereinafter, a circuit breaker is described as the equipment to be mechanically and electrically plugged onto a busbar stab. But it should be understood that any other electrical equipment or electric contact carrying means may be plugged onto the stab.
A circuit breaker line contact which receives a busbar stab may be comprised of a U-shaped clip having two arms. The clip arms open outwardly of the breaker and are normally spaced apart a distance such that the stab is forced between the arms of the clip and the clip arms are inwardly biased against the stab to make secure mechanical and electrical contact.
There are different manufacturers of circuit breakers, different sizes of circuit breakers, different styles of circuit breakers and different current ratings of circuit breakers. As a result, there are in common use circuit breakers having stab receiving line contacts with an opening between them that is oriented parallel to the long, length dimension of the circuit breaker (see U.S. Pat. No. 3,402,328 and 3,349,292) and other circuit breakers having stab receiving line contacts with an opening between them that is oriented parallel to the narrower, width dimension of the circuit breakers (see U.S. Pat. No. 3,767,977). Furthermore, the former type circuit breakers have conventionally been emplaced in one inch wide casings while the latter type circuit breakers have been emplaced in half-inch wide casings.
It is now conventional to design busbars with each individual stab thereon adapted to receive only one type of circuit breaker, i.e. with its line contacts oriented in only one direction and/or where the circuit breakers have half-inch wide or inch wide casings. (See U.S. Pat. No. 3,333,157 for one effort to deal with this.) Furthermore, each such busbar stab is usually able to support only one circuit breaker extending away from the stab in one direction and is not able to support two neighboring circuit breakers extending in the same direction.